Characterization of different regimens for initiating anagrelide in patients with essential thrombocythemia who are intolerant or refractory to their current cytoreductive therapy: results from the multicenter FOX study of 177 patients in France

Comparison of starting doses of anagrelide as a first-line therapy in patients with cytoreductive therapy-naïve essential thrombocythemia: difference between starting at 0.5 and 1.0 mg/day

Anagrelide is widely used for cytoreductive therapy in patients with essential thrombocythemia who are at high risk for thrombosis. The recommended starting dose in the package insert of anagrelide varies by country. A high starting dose leads to an early onset of action, but causes a higher incidence of adverse events. This relationship indicates that both the onset of action and side effects of anagrelide are dose dependent. We retrospectively compared the efficacy and safety of anagrelide as a first-line drug between patients with essential thrombocythemia who started at 0.5 or 1.0 mg/day. Incidence of total adverse events and anagrelide-related palpitation, discontinuation rates, and the median daily dose of anagrelide were lower in the 0.5 mg/day group than in the 1.0 mg/day group; however, comparable platelet-lowering effects were achieved in both groups. These data suggest that a low starting dose of anagrelide followed by dose escalation may result in fewer adverse events and lower discontinuation rates, while providing desirable platelet-lowering effects. Initiating anagrelide at a lower dose may be a useful approach in actual clinical practice.

Emerging drugs for essential thrombocythemia

Introduction: Despite our recent progress in the understanding of essential thrombocythemia (ET) pathogenesis, the therapeutic management of this disease has remained largely unchanged in the past decades. Treatment has mostly focused on decreasing the risk of complications, especially prevention of thrombotic or hemorrhagic events. Areas covered: Over recent years, the treatment options of ET have been expanding with some novel agents on the horizon. The classes of agents described in this review include targeted and immunomodulatory agents, such as JAK1/2 inhibitors, interferon-α, histone deacetylase inhibitors, telomerase inhibitors and human double minute 2 inhibitors. These compounds entered various stages of development, albeit the only portion of them is currently actively undergoing evaluation in clinical trials. In this review, we look at the current therapies and discuss novel agents available in the management of ET. Expert opinion: The drug development in ET possesses several challenges stemming from its relatively benign and prolonged disease course. Therapy focused on reducing the risk of thrombotic and hemorrhagic complications and symptom management needs to be chosen wisely as a vast majority of these patients have a near-normal life expectancy. To date, no therapy has shown effective and definitive alteration of the disease behavior. Although novel agents are in development and hopefully some of them will extend treatment armamentarium of ET, their exact role remains to be determined.

The Use of Anagrelide in Myeloproliferative Neoplasms, with Focus on Essential Thrombocythemia

Anagrelide (ANA) is a drug with specific platelet-lowering activity, used primarily in ET, registered as a second-line drug in essential thrombocythemia (ET) in Europe and in some countries as first-line therapy, in USA licensed by FDA for thrombocythemia in myeloproliferative neoplasms (MPN). The platelet-lowering efficacy is similar to that of hydroxycarbamide (HC), around 70 % complete response and 90 % partial response. Side effects are common, especially headache and tachycardia, but usually subside or disappear within a few weeks. Around 20 % of patients stop ANA therapy due to side effects or insufficient response. Studies of treatment patterns in Europe show that ANA is preferentially given to younger patients, probably because of the concern for a possible leukemogenic effect of the common first-line drug, HC. Only two randomized studies have compared the efficacy of ANA and HC in preventing thrombosis and haemorrhage, the larger of them showing a slightly better efficacy of HC, the other showing non-inferiority of ANA to HC. A recent observational 5-year study of 3600 patients shows a low and basically similar efficacy of ANA and other cytoreductive therapies in ET. ANA does not appear to inhibit fibrosis development, and probably due to its anticoagulation properties, the combination of ASA and ANA produces an increased rate of haemorrhage. Combination of ANA with HC or interferon (IFN) is feasible and effective in patients with insufficient platelet response to mono-therapy.

Management of side effects of BCR/ABL-negative chronic myeloproliferative neoplasm therapies. Focus on anagrelide

Although hydroxyurea is considered the first-line cytoreductive therapy in high-risk patients with polycythemia vera or essential thrombocythemia, approximately 20-25% of patients develop resistance or intolerance and they need an alternative therapy. Anagrelide is the treatment of choice in patients with essential thrombocythemia intolerant or with resistance to hydroxyurea. Anagrelide is usually well tolerated. Although there is concern about the increased risk of cardiac side effects, in most cases these are mild, and easily manageable. In this paper, the available evidence about the management of patients with myeloproliferative neoplasms, with a special focus on the side effects of drug therapies is reviewed.

Telomerase Inhibitor Imetelstat in Patients with Essential Thrombocythemia

BACKGROUND

Imetelstat, a 13-mer oligonucleotide that is covalently modified with lipid extensions, competitively inhibits telomerase enzymatic activity. It has been shown to inhibit megakaryocytic proliferation in vitro in cells obtained from patients with essential thrombocythemia. In this phase 2 study, we investigated whether imetelstat could elicit hematologic and molecular responses in patients with essential thrombocythemia who had not had a response to or who had had unacceptable side effects from prior therapies.

METHODS

A total of 18 patients in two sequential cohorts received an initial dose of 7.5 or 9.4 mg of imetelstat per kilogram of body weight intravenously once a week until attainment of a platelet count of approximately 250,000 to 300,000 per cubic millimeter. The primary end point was the best hematologic response.

RESULTS

Imetelstat induced hematologic responses in all 18 patients, and 16 patients (89%) had a complete hematologic response. At the time of the primary analysis, 10 patients were still receiving treatment, with a median follow-up of 17 months (range, 7 to 32 [ongoing]). Molecular responses were seen in 7 of 8 patients who were positive for the JAK2 V617F mutation (88%; 95% confidence interval, 47 to 100). CALR and MPL mutant allele burdens were also reduced by 15 to 66%. The most common adverse events during treatment were mild to moderate in severity; neutropenia of grade 3 or higher occurred in 4 of the 18 patients (22%) and anemia, headache, and syncope of grade 3 or higher each occurred in 2 patients (11%). All the patients had at least one abnormal liver-function value; all persistent elevations were grade 1 or 2 in severity.

CONCLUSIONS

Rapid and durable hematologic and molecular responses were observed in patients with essential thrombocythemia who received imetelstat. (Funded by Geron; ClinicalTrials.gov number, NCT01243073.).

[Efficacy and safety of anagrelide in treatment of essential thrombocythemia: multicenter, randomized controlled clinical trial]

OBJECTIVE

To evaluate the efficacy and safety of anagrelide in essential thrombocythemia (ET).

METHODS

Patients who diagnosed as ET according to the World Health Organization classification were enrolled. Each patient was assigned to take anagrelide hydrochloride capsule or hydroxyurea tablet by random 1∶1 ratio. Dose of anagrelide started at 2 mg/d, then increased gradually and the maximum dose was 10 mg/d until the platelet counts dropped to (100-400) × 10⁹/L, one month later gradually reduced to maintain dose. The dose of hydroxyurea was 1000 mg/d at beginning, then increased gradually, when platelet counts dropped to (100-400)×10⁹/L and kept for one month, reduced to maintain dose as 10 mg·kg⁻¹·d⁻¹. The observation period was 12 weeks.

RESULTS

A total of 222 patients were enrolled in seventeen centers (including 113 patients treated with anagrelide and 109 with hydroxyurea). Therapy efficacy can be evaluated in 198 patients (including 97 patients administered with anagrelide and 101 with hydroxyurea). At 12th weeks of therapy, the hematologic remission rate was 87.63% (85/97) in anagrelide group and 88.12% (89/107) in hydroxyurea group, the differences between the two groups were not significant (P=0.173). Treatment with anagrelide lowered the platelet counts by a median of 393 (362-1 339) × 10⁹/L from a median of 827 (562-1657) × 109/L at the beginning of the observation to 400(127-1130)×10⁹/L after 12 weeks (P<0.001), which were similar to the treatment result of hydroxyurea by a median drop of 398 (597-1846)× 10⁹/L (P=0.982). The median time to achieving response of anagrelide group was 7 (3-14) days, superior to that of hydroxyurea for 21 (14-28) significantly (P=0.003). Frequency of anagrelide related adverse events was 65.49 % (74/113), including cardiopalmus (36.28% ), headache (21.24% ), fatigue (14.16% ) and dizzy (11.50% ).

CONCLUSION

Anagrelide was effective in patients with ET which had similar hematologic remission rate to hydroxyurea and could take effect more quickly than hydroxyurea. Incidence of adverse events was undifferentiated between anagrelide and hydroxyurea, but anagrelide treatment had tolerable adverse effects and no hematologic toxicity.

[Efficacy and safety of anagrelide in treatment of essential thrombocythemia: multicenter, randomized controlled clinical trial]

OBJECTIVE

To evaluate the efficacy and safety of anagrelide in essential thrombocythemia (ET).

METHODS

Patients who diagnosed as ET according to the World Health Organization classification were enrolled. Each patient was assigned to take anagrelide hydrochloride capsule or hydroxyurea tablet by random 1∶1 ratio. Dose of anagrelide started at 2 mg/d, then increased gradually and the maximum dose was 10 mg/d until the platelet counts dropped to (100-400) × 10⁹/L, one month later gradually reduced to maintain dose. The dose of hydroxyurea was 1000 mg/d at beginning, then increased gradually, when platelet counts dropped to (100-400)×10⁹/L and kept for one month, reduced to maintain dose as 10 mg·kg⁻¹·d⁻¹. The observation period was 12 weeks.

RESULTS

A total of 222 patients were enrolled in seventeen centers (including 113 patients treated with anagrelide and 109 with hydroxyurea). Therapy efficacy can be evaluated in 198 patients (including 97 patients administered with anagrelide and 101 with hydroxyurea). At 12th weeks of therapy, the hematologic remission rate was 87.63% (85/97) in anagrelide group and 88.12% (89/107) in hydroxyurea group, the differences between the two groups were not significant (P=0.173). Treatment with anagrelide lowered the platelet counts by a median of 393 (362-1 339) × 10⁹/L from a median of 827 (562-1657) × 109/L at the beginning of the observation to 400(127-1130)×10⁹/L after 12 weeks (P<0.001), which were similar to the treatment result of hydroxyurea by a median drop of 398 (597-1846)× 10⁹/L (P=0.982). The median time to achieving response of anagrelide group was 7 (3-14) days, superior to that of hydroxyurea for 21 (14-28) significantly (P=0.003). Frequency of anagrelide related adverse events was 65.49 % (74/113), including cardiopalmus (36.28% ), headache (21.24% ), fatigue (14.16% ) and dizzy (11.50% ).

CONCLUSION

Anagrelide was effective in patients with ET which had similar hematologic remission rate to hydroxyurea and could take effect more quickly than hydroxyurea. Incidence of adverse events was undifferentiated between anagrelide and hydroxyurea, but anagrelide treatment had tolerable adverse effects and no hematologic toxicity.